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ISRN Electrochemistry
Volume 2013 (2013), Article ID 624163, 10 pages
http://dx.doi.org/10.1155/2013/624163
Research Article

A Study of the Initial Stages of Co Deposition on a Silver Electrode in Ammonia Medium Using an Electrochemical Quartz Crystal Microbalance

Laboratorio de Electroquímica, Centro de Investigación y Estudios de Posgrado, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Avenue Dr. Manuel Nava No. 6, Zona Universitaria, 78210 San Luis Potosi, SLP, Mexico

Received 6 November 2012; Accepted 4 December 2012

Academic Editors: C. M. Muller and W.-S. Zhang

Copyright © 2013 A. Montes-Rojas and A. L. Donjuan-Medrano. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The early stages of Co deposition on a silver electrode in ammonia medium were studied using cyclic voltammetry and chronoamperometry coupled with quartz crystal microbalance (EQCM) in ammonia solution. The results obtained by means of EQCM showed that during the initial stages of cobalt deposition a monolayer is formed on the substrate both in the underpotential and overpotential region, and this monolayer is formed at −600 mV and −980 mV. Once the cobalt deposition process starts, the growth is very fast making the investigation of the initial stages rather difficult. During this process, cobalt atoms transfer their two electrons through free species and not through cobalt hydroxide species adsorbed on the electrode as CoOH+ or Co(OH)2. In addition, it has been found that at potentials more positive than −600 mV, ammonia adsorption takes place on the substrate surface, and theses species are replaced when the cobalt atoms arrive at potentials more negative than −600 mV.